Chapter 1
Properties and Uses of Metal
Topics
1.0.0
Properties of Metal and Metal Alloys
2.0.0
Mechanical Properties
3.0.0
Corrosion Resistance
4.0.0
Ferrous Metals and Alloys
5.0.0
Nonferrous Metal and Alloys
6.0.0
Advanced Metal Identification
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Overview
As a steelworker, you will be looked upon as the subject matter expert on everything
metal. You will be expected to build, repair, and refurbish almost everything metal.
Knowing how to identify the metals you will be working with is one of the foundations of
your rate. To carry out these responsibilities skillfully, you must possess a sound
working knowledge of various metals and their properties.
Once you learn how to identify different metals confidently, beyond the
ferrous/nonferrous determination you learned in Steelworker Basic, you can make the
proper decisions pertaining to materials and tools you will need to complete the job. You
will work mainly with the ferrous metals iron and steel; however, you must also become
familiar with and be able to differentiate between the nonferrous metals. This chapter
will discuss the properties of different metals in greater detail and show how to use
simple tests to help identify common metals.
Objectives
When you have completed this chapter, you will be able to do the following:
1. Identify the properties of metal and metal alloys.
2. Describe the properties of metal and metal alloys.
3. Identify mechanical properties of metal.
4. Describe the concept of corrosion resistance.
5. Describe the different types of ferrous metals and alloys.
6. Describe the different types of nonferrous metals and alloys.
7. Interpret advanced metal identification.
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Prerequisites
None
This course map shows all of the chapters in Steelworker Advanced. The suggested
training order begins at the bottom and proceeds up. Skill levels increase as you
advance on the course map.
Welding Costs
S
T
E
E
L
Metal Fence System
W
O
R
K
Fabrication and Placement of Reinforcing Steel
E
R
A
D
Layout and Fabrication of Structural Steel and Pipe
V
A
N
C
Properties and Uses of Metal
E
D
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1.0.0 PROPERTIES of METAL and METAL ALLOYS
Metals in general have high electrical conductivity, thermal conductivity, luster and
density, and the ability to be deformed under stress without cleaving. Chemical
elements lacking these properties are classed as nonmetals. A few elements, known as
metalloids, sometimes behave like a metal and at other times like a nonmetal. Some
examples of metalloids are as follows: boron, arsenic, and silicon.
As you have already studied, metals are divided into two classes, ferrous and
nonferrous. Ferrous metals are those in the iron class and are magnetic in nature.
These metals consist of iron, steel, and alloys related to them. Nonferrous metals are
those that contain either no, or very small amounts of, ferrous metals. These are
generally divided into the aluminum, copper, magnesium, lead, and similar groups.
Although you will hardly ever work with pure metals, you need to be knowledgeable of
their properties because the alloys you will work with are combinations of pure metals.
Some of the pure metals discussed in this chapter are the base metals in these alloys,
especially iron, aluminum, and magnesium. Other metals discussed are the alloying
elements present in small quantities but important in their effect, including chromium,
molybdenum, titanium, and manganese.
An alloy is a mixture of two or more elements in solid solution in which the main element
is a metal. Most pure metals are either too soft, brittle, or chemically reactive for
practical use. Combining different ratios of metals as alloys modifies the properties of
the resultant metals to produce desirable characteristics. The reason for making alloys
is generally to create a less brittle, harder, corrosion resistant material, or one with a
more desirable color and luster.
Of the metallic alloys in use today, the alloys of iron (steel, stainless steel, cast iron, tool
steel, alloy steel) make up the largest proportion by both quantity and commercial value.
Iron alloyed with various proportions of carbon gives low-, mid- and high-carbon steels,
and as the carbon levels increase, ductility and toughness decrease. The addition of
silicon will produce cast irons, while the addition of chromium, nickel, and molybdenum
to carbon steels (more than 10%) results in stainless steels.
Aluminum, titanium, copper, and magnesium alloys are also significant in commercial
value. Copper alloys have been around since prehistory—bronze gave the Bronze Age
its name—and have many applications today, most importantly in electrical wiring. The
alloys of aluminum, titanium, and magnesium are valued for their high strength-toweight ratios. These materials are ideal for situations where high strength-to-weight
ratio is more important than material cost, such as in aerospace and some automotive
applications.
Alloys specially designed for highly demanding applications, such as jet engines, may
contain more than ten elements.
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Table 1-1 is a list of various elements and their symbols that compose metallic
materials.
Table 1-1 Symbols of Base Metals and Alloying Elements.
Element
Aluminum
Antimony
Cadmium
Carbon
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Molybdenum
Nickel
Phosphorus
Silicon
Sulfur
Tin
Tungsten
Vanadium
Zinc
Symbol
Al
Sb
Cd
C
Cr
Co
Cu
Fe
Pb
Mg
Mn
Mo
Ni
P
Si
S
Sn
W
V
Zn
Since you will work mostly with alloys, you need to understand their characteristics. The
characteristics of elements and alloys are explained in terms of physical, chemical,
electrical, and mechanical properties.
•
Physical properties relate to color, density, weight, and heat conductivity.
•
Chemical properties involve the behavior of the metal when placed in contact
with the atmosphere, salt water, or other substances.
•
Electrical properties encompass the electrical conductivity, resistance, and
magnetic qualities of the metal.
•
Mechanical properties relate to load-carrying ability, wear resistance, hardness,
and elasticity.
When selecting stock for a job, your main concern is the mechanical properties of the
metal. The various properties of metals and alloys were determined in the
manufacturers’ laboratories and by various societies interested in metallurgical
development. Charts presenting the properties of a particular metal or alloy are
available in many commercially published reference books. The charts provide
information on the melting point, tensile strength, electrical conductivity, magnetic
properties, and other properties of a particular metal or alloy. Simple tests can be
conducted to determine some of the properties of a metal; however, we normally use a
metal test only as an aid for identifying a piece of stock. Some of these methods of
testing are discussed later in this chapter.
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2.0.0 MECHANICAL PROPERTIES
Strength, hardness, toughness, elasticity, plasticity, brittleness, and ductility and
malleability are mechanical properties used as measurements of how metals behave
under a load. These properties are described in terms of the types of force or stress that
the metal must withstand and how these are resisted. Common types of stress are
compression, tension, shear, torsion, impact, or a combination of these stresses, such
as fatigue (Figure. 1-1).
Figure 1-1 — Stress applied to a material.
•
Compression stresses develop within a material when forces compress or crush
the material. A column that supports an overhead beam is in compression, and
the internal stresses that develop within the column are compression.
•
Tension (or tensile) stresses develop when a material is subject to a pulling load,
for example, when using a wire rope to lift a load or when using it as a guy to
anchor an antenna. “Tensile strength” is defined as resistance to longitudinal
stress or pull, and can be measured in pounds per square inch of cross section.
•
Shearing stresses occur within a material when external forces are applied along
parallel lines in opposite directions. Shearing forces can separate material by
sliding part of it in one direction and the rest in the opposite direction.
Some materials are equally strong in compression, tension, and shear. However, many
materials show marked differences; for example, cured concrete has a maximum
strength of 2,000 psi in compression, but only 400 psi in tension. Carbon steel has a
maximum strength of 56,000 psi in tension and compression but a maximum shear
strength of only 42,000 psi; therefore, when dealing with maximum strength, you should
always state the type of loading.
•
Fatigue is the tendency of a material to fail after repeated bending at the same
point. A repeatedly stressed material usually fails at a point considerably below
its maximum strength in tension, compression, or shear. For example, a thin
steel rod can be broken by hand by bending it back and forth several times in the
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same place; however, if the same force is applied in a steady motion (not bent
back and forth), the rod cannot be broken.
2.1.0 Strength
Strength is the property that enables a metal to resist deformation under load.
•
Compressive strength is the maximum load in compression a material will
withstand before a predetermined amount of deformation, or the ability of a
material to withstand pressures acting in a given plane. The compressive
strength of both cast iron and concrete is greater than their tensile strength. For
most materials, the reverse is true.
•
Tensile strength is defined as the maximum load in tension a material will
withstand before fracturing, or the ability of a material to resist being pulled apart
by opposing forces. Also known as ultimate strength, it is the maximum strength
developed in a metal in a tension test. (The tension test is a method for
determining the behavior of a metal under an actual stretch loading. This test
provides the elastic limit, elongation, yield point, yield strength, tensile strength,
and the reduction in area.) The tensile strength is the value most commonly
given for the strength of a material and is given in pounds per square inch (psi) or
kilo-Pascals (kPa). The tensile strength is the number of pounds of force required
to pull apart a bar of material 1.0 in. (25.4 mm) wide and 1.00 in. (25.4 mm) thick.
•
Shear strength is the ability of a material to resist being fractured by opposing
forces acting in a straight line but not in the same plane, or the ability of a metal
to resist being fractured by opposing forces not acting in a straight line.
•
Fatigue strength is the maximum load a material can withstand without failure
during a large number of reversals of load. For example, a rotating shaft that
supports a weight has tensile forces on the top portion of the shaft and
compressive forces on the bottom. As the shaft is rotated, there is a repeated
cyclic change in tensile and compressive strength. Fatigue strength values are
used in the design of aircraft wings and other structures subject to rapidly
fluctuating loads. Fatigue strength is influenced by microstructure, surface
condition, corrosive environment, and cold work. Impact strength is the ability of
a metal to resist suddenly applied loads and is measured in foot-pounds of force.
2.2.0 Hardness
Hardness is defined as resistance of metal to plastic deformation, usually by
indentation. However, the term may also refer to stiffness (temper) or to resistance to
scratching, abrasion, or cutting. It is the property of a metal which gives it the ability to
resist being permanently deformed (bent, broken, or have its shape changed) when a
load is applied. The greater the hardness of the metal, the greater resistance it has to
deformation. There are several methods of measuring the hardness of a material, so
hardness is always specified in terms of the particular test used.
The metals industry uses three types of hardness tests with accuracy: the Brinell,
Rockwell, and Vickers hardness tests. Since the definitions of metallurgic ultimate
strength and hardness are rather similar, it can generally be assumed that a strong
metal is also a hard metal.
These hardness tests measure a metal's hardness by determining the metal's
resistance to the penetration of a non-deformable ball or cone. The tests determine the
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depth to which such a ball or cone will sink into the metal under a given load within a
specific period of time.
Of these three tests, Rockwell is the most frequently used, the basic principle being that
a hard material can penetrate a softer one, so you measure the amount of penetration
and compare it to a scale.
In regular Rockwell testing the minor load is always 10 kgf (kilograms of force). The
major load can be any of the following loads: 60 kgf, 100 kgf, or 150 kgf. No Rockwell
hardness value is specified by a number alone. It must always be prefixed by a letter
signifying the value of the major load and type of penetrator (e.g., HRC 35). A letter has
been assigned for every possible combination of load and penetrator, as given in Table
1-2. Each test yields a Rockwell hardness value on your tester. Testers with dial gauges
have two sets of figures: red and black. When the diamond penetrator is used, the
readings are taken from the black divisions. When testing with any of the ball
penetrators, the readings are taken from the red divisions. Testers with digital displays
have a scale selection switch, allowing an automatic display of the Rockwell hardness
number on its screen.
Table 1-2 — Rockwell Hardness Scale.
Scale symbol
Penetrator
Load in Kilograms-Force (Kgf)
A*
Diamond tip*
60
B
1/16” ball
100
C
Diamond tip
150
D
Diamond tip
100
E
1/8” ball
100
F
1/16” ball
60
G
1/16” ball
150
H
1/8” ball
60
K
1/8” ball
150
L
1/4“ ball
60
M
1/4“ ball
100
P
1/4“ ball
150
R
1/2” ball
60
S
1/2” ball
100
V
1/2” ball
150
* Two scales – carbide and steel.
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The regular Rockwell scales are established such that an infinitely hard material will
read 100 on the diamond penetrator scales and 130 on the ball penetrator scales. One
regular Rockwell number represents a penetration of 0.002 mm (0.000080 inch).
Therefore, a reading of C60 indicates penetration from a minor to major load of (100 to
60 Rockwell points) x 0.002 mm = 0.080 mm or 0.0032 inch. A reading of B80 indicates
a penetration of (130 to 80 Rockwell points) x 0.002 = 0.100 mm or 0.004 inch (Figure
1-2).
A full explanation of the various methods used to determine the hardness of a material
is available in commercial books or books located in your base library. ASTM publishes
standards for every type of hardness test. Use these standards for the type of testing
you will be performing as they are the most up-to-date standards available.
Figure 1-2 — Rockwell testing.
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2.3.0 Toughness
Toughness is the property that enables a material to withstand shock and be deformed
without rupturing. Toughness may be considered as a combination of strength and
plasticity. Table 1-3 shows the order of some of the more common materials for
toughness as well as other properties.
Table 1-3 — Mechanical Properties of Metals/Alloys.
Toughness
Brittleness
Ductility
Malleability
Corrosion
Resistance
Copper
White cast iron
Gold
Gold
Gold
Nickel
Gray cast iron
Silver
Silver
Platinum
Iron
Hardened steel
Platinum
Aluminum
Silver
Magnesium
Bismuth
Iron
Copper
Mercury
Zinc
Manganese
Nickel
Tin
Copper
Aluminum
Bronzes
Copper
Lead
Lead
Lead
Aluminum
Aluminum
Zinc
Tin
Tin
Brass
Tungsten
Iron
Nickel
Cobalt
Structural steels
Zinc
Iron
Bismuth
Zinc
Tin
Zinc
Monel
Lead
Magnesium
Tin
Aluminum
Copper
Iron
Metals/alloys are ranked in descending order of having the property named in the column heading.
2.4.0 Elasticity
When a material has a load applied to it, the load causes the material to deform.
Elasticity is the ability of a material to return to its original shape after the load is
removed. Theoretically, the elastic limit of a material is the limit to which a material can
be loaded and still recover its original shape after the load is removed.
All materials are elastic to some extent. It may surprise you to learn that a piece of steel
is more elastic than a rubber band. The rubber band stretches more than the steel since
it is more easily strained, but the steel returns more nearly to its original shape and size
and is, therefore, more truly elastic.
2.5.0 Plasticity
Plasticity describes the ability of materials to undergo irreversible deformation without
fracture or damage. This property is the opposite of strength. By careful alloying of
metals, the combination of plasticity and strength is used to manufacture large structural
members. For example, should a member of a bridge structure become overloaded,
plasticity allows the overloaded member to flow, allowing the distribution of the load to
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other parts of the bridge structure. Sheet aluminum has a high plasticity, whereas tool
steel has a very low plasticity.
2.6.0 Brittleness
Brittleness is the opposite of plasticity. A brittle metal will break or shatter before it
deforms if bent or struck a sharp blow. Generally, brittle metals are high in compressive
strength but low in tensile strength. For example, cast iron is very brittle, so you would
not use cast iron for fabricating support beams in a bridge.
2.7.0 Ductility and Malleability
The properties known as ductility and malleability are special cases of plasticity.
•
Ductility is the property that makes it possible for a material to withstand
extensive permanent deformation from tension. It can be stretched or drawn out
into a thin wire. A very ductile metal such as copper or aluminum may be pulled
through dies to form wire.
•
Malleability is the property that makes it possible for a material to withstand
extensive permanent deformation from compression. It can be stamped,
hammered, or rolled into thin sheets.
Most metals that exhibit one of these properties also exhibit the other. However, this is
not always true. Lead, for example, is very malleable (it can be permanently deformed
in compression without breaking), but it is not ductile (it cannot be permanently
deformed in tension to any great extent).
3.0.0 CORROSION RESISTANCE
Corrosion resistance is the property that enables a material to resist entering into
chemical combination with other substances from attacks by atmospheric, chemical, or
electrochemical conditions. A high degree of corrosion resistance is very desirable in all
metals exposed to weather elements. Most metals are easily corroded, however, as
shown by the fact that pure metals occur only rarely in nature. One of the most common
examples of corrosion, sometimes called oxidation, is illustrated by the rusting of iron.
The presence of impurities or the presence of alloying elements may greatly alter the
corrosion resistance of a metal. For example, the zinc that is known as “commercially
pure” contains a small amount of impurities; this grade of zinc corrodes about 10,000
times as fast as zinc that is chemically pure. On the other hand, many alloys have been
developed for the particular purpose of increasing the corrosion resistance of the
material. For example, pure iron would be entirely unsuitable for use in boilers because
it has very poor resistance to corrosion, particularly at high temperatures; yet alloys
composed primarily of iron are used successfully for this service.
4.0.0 FERROUS METALS and ALLOYS
The following discussion is a refresher of SW Basic Chapter 1. Ferrous metals are
metals that contain iron. Ferrous metals appear in the form of cast iron, carbon steel,
and tool steel. The various alloys of iron, after undergoing certain processes, are pig
iron, gray cast iron, white iron, white cast iron, malleable cast iron, wrought iron, alloy
steel, and carbon steel. All these types of iron are mixtures of iron and carbon,
manganese, sulfur, silicon, and phosphorous. Other elements are also present, but in
amounts that do not appreciably affect the characteristics of the metal. Normally, ferrous
metals are magnetic and nonferrous metals are nonmagnetic.
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4.1.0 Iron
Pure iron rarely exists outside of the laboratory. Iron is produced by reducing iron ore to
pig iron by using a blast furnace. From pig iron, many other types of iron and steel are
produced by the addition or deletion of carbon and alloys. The following paragraphs
discuss the different types of iron and steel that can be made from iron ore.
4.1.1 Pig Iron
Pig iron is about 93% iron, from 3% to 5% carbon, with various amounts of other
elements. Pig iron is comparatively weak and brittle; therefore, it has a limited use as is
(cast iron pipe and some fittings and valves), and approximately ninety percent of it is
refined to produce steel.
4.1.2 Wrought Iron
Wrought iron is almost pure iron. It is made from pig iron in a puddling furnace and has
a carbon content of less than 0.08 percent. Carbon and other elements present in pig
iron are taken out, leaving almost pure iron. In the process of manufacture, some slag is
mixed with iron to form a fibrous structure in which long stringers of slag, running
lengthwise, are mixed with long threads of iron. Because of the presence of slag,
wrought iron resists corrosion and oxidation which cause rusting.
The chemical analyses of wrought iron and mild steel are just about the same. The
difference comes from the properties controlled during the manufacturing process.
Wrought iron can be gas and arc welded, machined, plated, and easily formed;
however, it has a low hardness and a low fatigue strength.
4.1.3 Cast Iron
Cast iron is a manmade alloy of iron, carbon, and silicon. A portion of the carbon exists
as free carbon or graphite. Cast iron is any iron containing greater than 2% carbon
alloy, with most cast irons ranging between 2.1% to 4% by weight. Cast iron has a highcompressive strength and good wear resistance; however, it lacks ductility, malleability,
and impact strength. Alloying it with nickel, chromium, molybdenum, silicon, or
vanadium improves toughness, tensile strength, and hardness. A malleable cast iron is
produced through a prolonged annealing process.
4.1.4 Ingot Iron
Ingot iron is a commercially pure (99.85% iron), easily formed iron, with good ductility
and corrosion resistance. The chemical analysis and properties of ingot iron are
practically the same as the lowest carbon steel. The lowest carbon steel, known as
dead-soft, has about 0.06% more carbon than ingot iron.
Carbon content in iron is considered an impurity; carbon content in steel is considered
an alloying element. The primary use for ingot iron is for galvanized and enameled
sheet.
4.2.0 Steel
Steel is an alloy consisting mostly of iron, with carbon content between 0.2% and 2.1%
by weight, depending on the grade. Steel contains less carbon than cast iron (2.1% to
4%), but considerably more than wrought iron (less than 0.08%). Basic carbon steels
are alloyed with other elements, such as chromium and nickel, to increase certain
physical properties of the metal. Steel can be machined, welded, and forged, all to
varying degrees, depending on the type of steel.
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Steels and other metals are classified based on method of manufacture, method of
shaping, method of heat treatment, properties, intended use, and chemical composition.
In addition, certain steels and other metals are often referred to by trade names.
Probably the most reasonable way to classify steels is by their chemical composition.
Steels that derive their properties primarily from the presence of carbon are referred to
merely as “steels” or sometimes as “plain carbon steels.” Steels that derive their
properties primarily from the presence of some alloying element other than carbon are
referred to as “alloys” or “alloy steels.”
4.2.1 Low-Carbon Steel
Low-carbon steel (0.05% to 0.30% carbon) is tough and ductile, and can be rolled,
punched, sheared, and worked when either hot or cold. It is easily machined and can
readily be welded by all methods. It does not respond to heat-treating; however, it can
easily be case hardened.
4.2.2 Medium-Carbon Steel
Medium-carbon steel (0.30% to 0.45% carbon) is strong and hard but cannot be welded
or worked as easily as the low-carbon steels. It may be heat-treated after fabrication. It
is used for general machining and forging of parts that require surface hardness and
strength, such as crane hooks, axles, shafts, setscrews, and so on. Medium-carbon
steel is made in bar form in the cold-rolled or the normalized and annealed condition.
During welding, the weld zone will become hardened if cooled rapidly and must be
stress-relieved after welding.
4.2.3 High-Carbon Steel/Very High-Carbon Steel
High-carbon steel (0.45% to 0.75% carbon) and very high-carbon steel (0.75% to 1.70%
carbon) respond well to heat treatment and can be welded with difficulty, but the
welding must be done using specific processes due to the hardening effect of heat at
the welded joint. This steel is used for the manufacture of drills, taps, dies, springs, and
other machine tools and hand tools that are heat-treated after fabrication to develop the
hard structure necessary to withstand high shear stress and wear. It is manufactured in
bar, sheet, and wire forms, and in the annealed or normalized condition in order to be
suitable for machining before heat treatment.
Tool steel (0.70% to 1.40% carbon) refers to a special variety of carbon and alloy steels
particularly well suited to be made into tools. Tool steels are made to a number of
grades for different applications. Choice of grade depends on, among other things,
whether a keen cutting edge is necessary, abrasion resistance is paramount, or the tool
must withstand impact loading encountered with such tools as axes, pickaxes, and
quarrying implements.
Tool steel is used to manufacture chisels, shear blades, cutters, large taps, woodturning
tools, blacksmith’s tools, razors, and similar parts where high hardness is required to
maintain a sharp cutting edge. It is very difficult to weld due to the high carbon content.
A spark test shows a moderately large volume of white sparks having many fine,
repeating bursts.
4.2.4 Low-Alloy, High-Strength, Tempered Structural Steel
This is a special low-carbon steel, containing specific small amounts of alloying
elements, that is quenched and tempered to get a yield strength greater than 50,000 psi
and tensile strengths of 70,000 to 120,000 psi. Structural members made from these
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high-strength steels may have smaller cross-sectional areas than common structural
steels and still have equal or greater strength. Additionally, these steels are normally
more corrosion and abrasion resistant. High-strength steels are covered by ASTM
specifications.
NOTE
This type of steel is much tougher than low-carbon steels. Shearing machines for this
type of steel must have twice the capacity than that required for low-carbon steels.
4.2.5 Stainless Steel
This type of steel is classified by the American Iron and Steel Institute (AISI) into two
general series named the 200-300 series and the 400 series. Each series includes
several types of steel with different characteristics.
4.2.5.1 200-300 Series
The 200-300 series of stainless steel is known as austenitic. Austenitic wrought
stainless steel is classified in three groups:
•
The AISI 200 series (alloys of iron-chromium-nickel-manganese)
•
The AISI 300 series (alloys of iron-chromium-nickel)
•
Nitrogen-strengthened alloys
Carbon content is usually low (0.15% or less), and the alloys contain a minimum of 16%
chromium with sufficient nickel and manganese to provide an austenitic structure at all
temperatures from the cryogenic region to the melting point of the alloy.
Nitrogen-strengthened austenitic stainless steels are alloys of chromium-manganesenitrogen; some grades also contain nickel. Yield strengths of these alloys (annealed)
are typically 50% higher than those of the non-nitrogen-bearing grades. They are
nonmagnetic, and most remain so, even after severe cold working.
Like carbon, nitrogen increases the strength of a steel, but unlike carbon, nitrogen does
not combine significantly with chromium in a stainless steel. This combination, which
forms chromium carbide, reduces the strength and corrosion resistance of an alloy.
Until recently, metallurgists had difficulty adding controlled amounts of nitrogen to an
alloy. The development of the argon-oxygen decarburization (AOD) method has made
possible strength levels formerly unattainable in conventional annealed stainless alloys.
Austenitic stainless steels are generally used where corrosion resistance and toughness
are primary requirements. Typical applications include shafts, pumps, fasteners, and
piping in seawater, and equipment for processing chemicals, food, and dairy products.
The most well known types of steel in this series are the 302 and 304. They are
commonly called 18-8 because they are composed of 18% chromium and 8% nickel.
The chromium nickel steels are the most widely used and are normally nonmagnetic.
4.2.5.2 400 Series
The 400 series of steel is subdivided according to their crystalline structure into two
general groups. One group is known as ferritic chromium and the other group as
martensitic chromium.
Ferritic chromium contains 10.5% to 27% chromium and 0.08% to 0.20% carbon. Low in
carbon content but generally higher in chromium than the martensitic grades, these
steels cannot be hardened by heat treating and are only moderately hardened by cold
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working. Ferritic stainless steels are the straight chromium grades of stainless steel
since they contain no nickel; they are magnetic and retain their basic microstructure up
to the melting point if sufficient Cr and Mo are present. In the annealed condition,
strength of these grades is approximately 50% higher than that of carbon steels.
Ferritic stainless steels are typically used where moderate corrosion resistance is
required and where toughness is not a major need. They are also used where chloride
stress-corrosion cracking may be a problem because they have high resistance to this
type of corrosion failure. In heavy sections, achieving sufficient toughness is difficult
with the higher-alloyed ferritic grades. Typical applications include automotive trim and
exhaust systems and heat-transfer equipment for the chemical and petrochemical
industries.
Martensitic chromium contains from 11.5 to 18% chromium, 0.15% to 1.2% carbon, and
up to 2.5% nickel. They are magnetic, can be hardened by heat treatment, and have
high strength and moderate toughness in the hardened-and-tempered condition.
Forming should be done in the annealed condition. Martensitic stainless steels are less
resistant to corrosion than the austenitic or ferritic grades. Two types of martensitic
steels, 416 and 420F, have been developed specifically for good machinability.
Martensitic stainless steels are used where strength and/or hardness are of primary
concern and where the environment is relatively mild from a corrosive standpoint. These
alloys are typically used for bearings, molds, cutlery, medical instruments, aircraft
structural parts, and turbine components. Type 420 is used increasingly for molds for
plastics and for industrial components requiring hardness and corrosion resistance.
4.2.6 Alloy Steels
Steels that derive their properties primarily from the presence of some alloying element
other than carbon are called alloys or alloy steels. Alloy steels always contain traces of
other elements. Among the more common alloying elements are nickel, chromium,
vanadium, silicon, and tungsten. One or more of these elements may be added to the
steel during the manufacturing process to produce the desired characteristics.
Alloy steels may be produced in structural sections, sheets, plates, and bars for use in
the “as-rolled” condition. Better physical properties are obtained with these steels than
are possible with hot-rolled carbon steels. These alloys are used in structures where the
strength of material is especially important, such as bridge members, railroad cars,
dump bodies, dozer blades, and crane booms. The following paragraphs briefly
describe some common alloy steels.
4.2.6.1 Nickel Steels
These steels contain from 3.5% nickel to 5% nickel. The nickel increases the strength
and toughness of these steels. Nickel steel containing more than 5% nickel has an
increased resistance to corrosion and scale. Nickel steel is used in the manufacture of
aircraft parts, such as propellers and airframe support members.
4.2.6.2 Chromium Steels
These steels have chromium added to improve hardening ability, wear resistance, and
strength. These steels contain between 0.20% to 0.75% chromium and 0.45% carbon or
more. Some of these steels are so highly resistant to wear that they are used for the
races and balls in anti-friction bearings. Chromium steels are highly resistant to
corrosion and scale.
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4.2.6.3 Chrome Vanadium Steel
This steel has the maximum amount of strength with the least amount of weight. Steels
of this type contain from 0.15% to 0.25% vanadium, 0.6% to 1.5% chromium, and 0.1%
to 0.6% carbon. Common uses are for crankshafts, gears, axles, and other items that
require high strength. This steel is used also in the manufacture of high quality hand
tools, such as wrenches and sockets.
4.2.6.4 Tungsten Steel
This is a special alloy that has the property of red hardness, that is, the ability to
continue to cut after it becomes red-hot. A good grade of this steel contains from 13% to
19% tungsten, 1% to 2% vanadium, 3% to 5% chromium, and 0.6% to 0.8% carbon.
Because this alloy is expensive to produce, its use is largely restricted to the
manufacture of drills, lathe tools, milling cutters, and similar cutting tools.
4.2.6.5 Molybdenum
This is often used as an alloying agent for steel in combination with chromium and
nickel. The molybdenum adds toughness to the steel. It can be used in place of
tungsten to make the cheaper grades of high-speed steel and in carbon molybdenum
high-pressure tubing.
4.2.6.6 Manganese Steels
The amount of manganese used depends upon the properties desired in the finished
product. Small amounts of manganese produce strong, free-machining steels. Larger
amounts (between 2% and 10%) produce a somewhat brittle steel, while still larger
amounts (11% to 14%) produce a steel that is tough and very resistant to wear after
proper heat treatment.
5.0.0 NONFERROUS METALS and ALLOYS
Nonferrous metals contain either no iron or only insignificant amounts used as an alloy.
Some of the more common nonferrous metals Steelworkers work with include copper,
brass, bronze, copper-nickel alloys, lead, zinc, tin, aluminum, and Duralumin. All
nonferrous metals are nonmagnetic.
5.1.0 Copper
Copper and its alloys have many desirable properties. Copper is ductile, malleable,
hard, tough, strong, wear resistant, machinable, weldable, and corrosion resistant. It
also has high-tensile strength, fatigue strength, and thermal and electrical conductivity.
Copper is one of the easier metals to work with, but you must be careful because it
easily becomes work-hardened. However, this condition can be remedied by annealing,
that is, heating it to a cherry red, and then letting it cool; this process restores it to a
softened condition. Annealing and softening are the only heat-treating procedures that
apply to copper. Seams in copper are joined by riveting, silver brazing, bronze brazing,
soft soldering, gas welding, or electrical arc welding. Copper is frequently used to give a
protective coating to sheets and rods and to make ball floats, containers, and soldering
coppers.
5.2.0 True Brass
Brass is an alloy of copper and zinc, with additional elements such as aluminum, lead,
tin, iron, manganese, or phosphorus added to give the alloy specific properties. Naval
NAVEDTRA 14251A
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rolled brass (Tobin bronze) contains about 60% copper, 39% zinc, and 0.75% tin. This
brass is highly corrosion resistant and is practically impurity free.
Brass sheets and strips are available in several grades: soft, 1/4 hard, 1/2 hard, full
hard, and spring grades. The process of cold rolling creates hardness. All grades of
brass can be softened by annealing at a temperature of 550°F to 600°F, then allowing it
to cool by itself without quenching, but be careful not to overheat; overheating can
destroy the zinc in the alloy.
5.3.0 Bronze
Bronze is a combination of 84% copper and 16% tin, and was the best metal available
before steel-making techniques were developed. Many complex bronze alloys are now
available, containing such elements as zinc, lead, iron, aluminum, silicon, and
phosphorus, so today, the name bronze is applied to any copper-based alloy that looks
like bronze. In many cases, there is no real distinction between the composition of
bronze and that of brass.
5.4.0 Copper-Nickel Alloys
Nickel is used in these alloys to make them strong, tough, and resistant to wear and
corrosion. Because of their high resistance to corrosion, copper-nickel alloys, containing
70% copper and 30% nickel or 90% copper and 10% nickel, are used for saltwater
piping systems. Small storage tanks and hot water reservoirs are constructed of a
copper-nickel alloy available in sheet form. Copper-nickel alloys should be joined by
metal-arc welding or by brazing.
5.5.0 Lead
Lead is a heavy metal that weighs about 710 pounds per cubic foot. In spite of its
weight, lead is soft, malleable, and available in pig and sheet form (in rolls). Lead’s
surface is grayish, but after scratching or scraping it, you can see that the actual color of
the metal is white. Because it is soft, lead is used as backing material when punching
holes with a hollow punch or when forming shapes by hammering copper sheets. Sheet
lead is also used to line sinks or protect bench tops where a large amount of acid is
used. Lead-lined pipes are used in systems that carry corrosive chemicals. Frequently,
lead is used in alloyed form to increase its low-tensile strength. Alloyed with tin, lead
produces a soft solder; when added to metal alloys, lead improves their machinability.
CAUTION
When working with lead, you must take proper precautions because the dust, fumes, or
vapors from it are highly poisonous.
5.6.0 Zinc
You often see zinc used on iron or steel in the form of a protective coating called
galvanizing. Zinc is also used in soldering fluxes and die-castings, and as an alloy in
making brass and bronze.
5.7.0 Tin
Tin has many important uses as an alloy. It can be alloyed with lead to produce softer
solders and with copper to produce bronze. Tin-based alloys have a high resistance to
corrosion, low-fatigue strength, and a compressive strength that accommodates light or
NAVEDTRA 14251A
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medium loads. Tin, like lead, has a good resistance to corrosion and has the added
advantage of not being poisonous; however, it has a tendency to decompose when
subjected to extremely low temperatures.
5.8.0 Aluminum
Aluminum is easy to work with and has a good appearance. It is light in weight with a
high strength per unit weight. A disadvantage is that its tensile strength is only one third
of iron’s and one fifth of annealed mild steel’s. Aluminum alloys usually contain at least
90% aluminum, while the addition of silicon, magnesium, copper, nickel, or manganese
can raise the strength of the alloy to that of mild steel. In its pure state, aluminum is soft,
with a strong affinity for gases. Alloying elements are used to overcome these
disadvantages, but the alloys, unlike the pure aluminum, corrode unless given a
protective coating. Threaded parts made of aluminum alloy should be coated with an
anti-seize compound to prevent sticking caused by corrosion.
5.9.0 Duralumin
Developed in 1903, Duralumin is one of the first of the strong structural aluminum
alloys; it was used in zeppelins, including the Hindenburg. Over the past hundred years,
with the development of a variety of different wrought-aluminum alloys, a numbering
system was adopted, with digits indicating the major alloying element and the coldworked or heat-treated condition of the metal. Today, the name Duralumin is rarely
used, and it is now classified in the metal working industries as 2017-T4; the T4
indicates heat treated.
5.10.0 Alclad
This is a protective covering consisting of a thin sheet of pure aluminum rolled onto the
surface of an aluminum alloy during manufacture. Zinc chromate is a protective
covering that can be applied to an aluminum surface as needed, or used as a primer on
steel surfaces for a protective coating
5.11.0 Monel
Monel is an alloy in which nickel is the major element. It contains from 64% to 68%
nickel, about 30% copper, and small percentages of iron, manganese, and cobalt.
Monel is harder and stronger than either nickel or copper, and has high ductility. It
resembles stainless steel in appearance and has many of its qualities. The strength
combined with a high resistance to corrosion makes Monel an acceptable substitute for
steel in systems where corrosion resistance is the primary concern. Nuts, bolts, screws,
and various fittings are made of Monel. This alloy can be forged, welded, and worked
cold. If worked in the temperature range between 1200°F and 1600°F, it becomes “hot
short” or brittle.
5.12.0 K-Monel
K-monel is a special type of alloy developed for greater strength and hardness than
Monel. In strength, it is comparable to heat-treated steel, and is used for instrument
parts that must resist corrosion.
5.13.0 Inconel
A high-nickel alloy often used in the exhaust systems of aircraft engines, Inconel is
composed of 78.5% nickel, 14% chromium, 6.5% iron, and 1% of other elements. It
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offers good resistance to corrosion and retains its strength at high operating
temperatures.
6.0.0 ADVANCED METAL IDENTIFICATION
This topic is an expansion of the material we discussed in SW Basic Chapter 1; through
repetition, you will become more familiar with these identification processes.
Many methods are used to identify a piece of metal. Identification is necessary when
selecting a metal for use in fabrication or in determining its weldability. Some common
methods used for field identification are surface appearance, spark test, chip test, and
use of a magnet.
6.1.0 Surface Appearance
It is possible to identify several metals by their surface appearance. Although
examination of the surface does not usually give you enough information to classify the
metal exactly, it will often give you enough information to allow you to identify the group
to which the metal belongs. Even this much identification is helpful since it will limit the
number of tests required for further identification.
In trying to identify a piece of metal by its surface appearance, consider both the color
and the texture of the surface. Table 1-4 indicates the surface colors of some of the
more common metals.
Referring to the table, you can see that the outside appearance of a metal helps to
identify and classify metal, while newly fractured or freshly filed surfaces offer additional
clues.
•
Cast iron and malleable iron usually show evidence of the sand mold.
•
Low-carbon steel often shows forging marks.
•
High-carbon steel shows either forging or rolling marks.
Feeling the surface may provide another clue.
•
Stainless steel is slightly rough in the unfinished state.
•
The surfaces of wrought iron, copper, brass, bronze, nickel, and Monel are
smooth.
•
Lead is smooth but has a velvety appearance.
When the surface appearance of a metal does not give enough information to positively
identify it, other identification tests become necessary. Some of these tests are
complicated and require equipment Seabees do not usually have; however, some tests
are fairly simple and reliable when done by a skilled person. Three of these tests are the
spark test, chip test, and magnetic test.
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Metals
Table 1-4 — Surface Colors of Some Common Metals.
Color of unfinished,
Color and structure of
Color of freshly
unbroken surface
newly fractured surface
filed surface
White cast iron Dull gray
Silver white; crystalline
Silvery white
Light silvery gray
Gray cast iron
Dull gray
Dark gray; crystalline
Malleable iron
Dull gray
Dark gray; finely crystalline Light silvery gray
Wrought iron
Light gray
Bright gray
Light silvery gray
Low-carbon
and cast steel
Dark gray
Light gray
Bright silvery gray
Stainless steel
Dark gray
Medium gray
Bright silvery gray
Copper
Reddish brown to
green
Bright red
Bright copper
color
Brass and
bronze
Reddish yellow,
yellow-green, of brown
Red to yellow
Reddish yellow to
yellowish white
Aluminum
Light gray
White; finely crystalline
White
Monel metal
Dark gray
Light gray
Light gray
Nickel
Dark gray
Off-white
Bright silvery
white
Lead
White to gray
Light gray; crystalline
White
6.2.0 Spark Test
The spark test is a method of classifying steels and iron according to their composition
by observing the sparks formed when the metal is held against a high-speed grinding
wheel. This test does not replace chemical analysis, but it is a very convenient and fast
method of sorting mixed steels whose spark characteristics are known.
When held lightly against a grinding wheel, the different kinds of iron and steel produce
sparks that vary in length, shape, and color. The grinding wheel should be run to give a
surface speed of at least 5000 ft (1525 m) per minute to get a good spark stream.
Grinding wheels should be hard enough to wear for a reasonable length of time, yet soft
enough to keep a free-cutting edge. Spark testing should be done in subdued light since
the color of the spark is important. In all cases, it is best to use standard known metal
samples to compare their sparks with that of the unknown test sample.
Spark testing is not of much use on nonferrous metals such as coppers, aluminums,
and nickel-base alloys since they do not exhibit spark streams of any significance.
However, this is one way to separate ferrous and nonferrous metals.
The spark resulting from the test should be directed downward and studied. The color,
shape, length, and activity of the sparks relate to characteristics of the material being
tested (Figure 1-3).
NAVEDTRA 14251A
1-20
Figure 1-3 — Terms used in spark testing.
The spark stream has specific characteristics which can be identified.
•
The straight lines are called carrier lines. They are usually solid and continuous.
•
At the end of the carrier line, the spark stream may divide into three short lines,
or forks.
•
If the spark stream divides into more lines at the end, it is called a sprig.
•
Sprigs also occur at different places along the carrier line. These are called either
star or fan bursts.
•
In some cases, the carrier line will enlarge slightly for a very short length,
continue, and perhaps enlarge again for a short length. When these heavier
portions occur at the end of the carrier line, they are called spear points or buds.
One big advantage of this test is that it can be applied to metal in all stages - bar stock
in racks, machined forgings, or finished parts. The spark test is best conducted by
holding the steel stationary and touching a high speed portable grinder to the specimen
with sufficient pressure to throw a horizontal spark stream about 12.00 in. (30.48 cm)
long and at right angles to the line of vision. Wheel pressure against the work is
important because increasing pressure will raise the temperature of the spark stream
and give the appearance of higher carbon content. The sparks near and around the
wheel, the middle of the spark stream, and the reaction of incandescent particles at the
end of the spark stream should be observed. Sparks produced by various metals are
shown in Figure 1-4.
NAVEDTRA 14251A
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Figure 1-4 — Spark patterns formed by common metals.
Low-carbon steel has a long spark stream (about 70 inches normally), and its volume is
moderately large, while in high-carbon steel, the stream is shorter (about 55 inches) and
larger in volume. The few sparklers that may occur at any place in low-carbon steel are
forked, while in high-carbon steel the sparklers are small and repeating, and some of
the shafts may be forked. Both will produce a white spark stream.
White cast iron produces a spark stream approximately 20 inches in length. The volume
of sparks is small with many small and repeating sparklers. The color of the spark
stream close to the wheel is red, while the outer end of the stream is straw colored.
Gray cast iron produces a stream of sparks about 25 inches in length. It is small in
volume with fewer sparklers than white cast iron. The sparklers are small and repeating.
Part of the stream near the grinding wheel is red, and the outer end of the stream is
straw colored.
The malleable iron spark test will produce a spark stream about 30 inches in length. It is
of a moderate volume with many small, repeating sparklers toward the end of the
stream. The entire stream is straw colored.
The wrought iron spark test produces a spark stream about 65 inches in length. The
stream is of large volume with few sparklers. The sparklers show up toward the end of
the stream and are forked. The stream next to the grinding wheel is straw colored, while
the outer end of the stream is a bright red.
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Stainless steel produces a spark stream approximately 50 inches in length, of moderate
volume, with few sparklers. The sparklers are forked. The stream next to the wheel is
straw colored. The sparks form wavy streaks with no sparklers.
Monel metal forms a spark stream almost identical to that of nickel and must be
identified by other means.
6.3.0 Chip Test
The chip test or chisel test may also be used to identify metals. The only tools required
are a hammer and a cold chisel. Use the cold chisel to hammer on the edge or corner of
the material being examined.
The ease of producing a chip is the indication of the hardness of the metal. If the chip is
continuous, it is indicative of a ductile metal, whereas if chips break apart, it indicates a
brittle material. On such materials as aluminum, mild steel, and malleable iron, the chips
are continuous. They are easily chipped and the chips do not tend to break apart. The
chips for gray cast iron are so brittle that they become small, broken fragments. On
high-carbon steel, the chips are hard to obtain because of the hardness of the material,
but can be continuous. Information given in Table 1-5 can help you identify various
metals by the chip test.
Table 1-5 — Metal Identification by Chip Test.
Metals
Chip characteristics
White cast iron
Chips are small brittle fragments. Chipped surfaces
are not smooth.
Gray cast iron
Chips are about 1/8 inch in length. Metal not easily
chipped; chips break off and prevent smooth cut.
Malleable iron
Chips vary from 1/4 to 3/8 inch in length. Metal is
tough and hard to chip.
Wrought iron
Chips have smooth edges. Metal is easily cut or
chipped, and a chip can be made as a continuous
strip.
Low-carbon and cast steel
Chips have smooth edges. Metal is easily cut or
chipped, and a chip can be taken off as a continuous
strip.
High-carbon steel
Chips show a fine grain structure. Edges of chips are
lighter in color than chips of low-carbon steel. Metal
is hard, but can be chipped in a continuous strip.
Copper
Chips are smooth, with sawtooth edges where cut.
Metal is easily cut as a continuous strip.
Brass and bronze
Chips are smooth, with sawtooth edges. These
metals are easily cut, but chips are more brittle than
chips of copper. Continuous strip is not easily cut.
Aluminum and aluminum alloys Chips are smooth, with sawtooth edges. A chip can
be cut as a continuous strip.
Monel
Chips have smooth edges. Continuous strip can be
cut. Metal chips easily.
Nickel
Chips have smooth edges. Continuous strip can be
cut. Metal chips easily
Lead
Chips of any shape may be obtained.
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6.4.0 Magnetic Test
The magnetic test can be quickly performed using a small pocket magnet. With
experience, it is possible to judge a strongly magnetic material from a slightly magnetic
material. The nonmagnetic materials are easily recognized. Strongly magnetic materials
include the carbon and low-alloy steels, iron alloys, pure nickel, and martensitic
stainless steels. A slightly magnetic reaction is obtained from Monel and high nickel
alloys and the stainless steel of the 18 chrome-8 nickel type when cold worked, such as
in a seamless tube. Nonmagnetic materials include copper-base alloys, aluminum-base
alloys, zinc-base alloys, annealed 18 chrome-8 nickel stainless, magnesium, and the
precious metals.
Summary
This chapter discussed how to identify the various metals and their properties. You also
learned how to describe corrosion resistance and identify different types of ferrous and
nonferrous metals and alloys, and how to use simple tests to help identify common
metals. As always, use the manufacturers’ operator manuals for the specific setup and
safety procedures of the equipment you will be using, and wear the proper personal
protective equipment.
NAVEDTRA 14251A
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Review Questions 6HOHFWWKH&RUUHFW5HVSRQVH
1.
(True or False) Steelworkers work primarily with iron and steel.
A.
B.
2.
Which symbol is NOT a chemical symbol for a metal?
A.
B.
C.
D.
3.
Load carrying
Heat conductivity
Magnetic qualities
Wear resistance
(True or False)Tension stresses are also known as “tensile stresses.”
A.
B.
7.
True
False
Which property is an electrical property of an alloy?
A.
B.
C.
D.
6.
True
False
(True or False)The characteristics of elements and alloys are terms of physical,
chemical, electrical, and mechanical properties.
A.
B.
5.
Al
Fe
Cr
Br
(True or False)An alloy is defined as a substance having metallic properties that
is composed of two or more elements.
A.
B.
4.
True
False
True
False
Having the capacity to conduct heat and electricity, to be lustrous, and to be
deformed or permanently shaped at room temperature are properties of which
substance?
A.
B.
C.
D.
Metalloid
Nonmetal
Metal
Chemical
NAVEDTRA 14251A
1-25
8.
Which elements sometimes behave like metals and at other times like
nonmetals?
A.
B.
C.
D.
9.
Which property is NOT a mechanical property of a metal alloy?
A.
B.
C.
D.
10.
Compression load
Twisting action
Shearing action
Pulling load
Carbon steel has an ultimate tension and compression strength of what
maximum psi?
A.
B.
C.
D.
13.
Compression
Shearing
Tension
Torsion
Tensile stresses are developed when a material is subjected to what type of
force?
A.
B.
C.
D.
12.
Sturdiness
Elasticity
Weight
Hardness
Within a column that is supporting a roof beam, internal stresses develop. This
condition is referred to by what term?
A.
B.
C.
D.
11.
Carbon and sulfur
Titanium and iron
Silver and tin
Boron and silicon
42,000
48,000
56,000
66,000
What term is used to describe the tendency of a metal to fail after repeated
stressing at the same point?
A.
B.
C.
D.
Tension
Ductility
Malleability
Fatigue
NAVEDTRA 14251A
1-26
14.
What term is used to describe the mechanical property of a metal that allows it to
be drawn out into a thin wire?
A.
B.
C.
D.
15.
What characteristic is responsible for the limited use of pig iron?
A.
B.
C.
D.
16.
High carbon
Medium carbon
Mild carbon
Low carbon
Steel containing 10.5% to 27% chromium, .08% to .20% carbon, and no nickel is
in what group and series of stainless steel?
A.
B.
C.
D.
20.
Re-melting
Annealing
Plating
Alloying
What group of steel is best suited for the manufacture of crane hooks and axles?
A.
B.
C.
D.
19.
Hardness
Tensile strength
Toughness
All of the above
What process is used to produce malleability in cast iron?
A.
B.
C.
D.
18.
It is comparatively weak and brittle.
It is difficult to re-melt.
It cannot be combined with other metals.
It is used exclusively for manufacturing cast iron pipe.
When cast iron is alloyed with nickel, chromium, molybdenum, silicon, or
vanadium, which characteristic is enhanced?
A.
B.
C.
D.
17.
Malleability
Toughness
Brittleness
Ductility
Martensitic-chromium of the 300 series
Austenitic chromium-nickel of the 300 series
Ferritic-austenite of the 400 series
Ferritic-chromium of the 400 series
For what purpose is nickel added to low-alloy nickel steel?
A.
B.
C.
D.
To increase strength and toughness
To reduce the chromium requirement due to weight limitations
To increase its ability to cut other metals after the steel becomes red-hot
To permit the steel to be drawn into wire
NAVEDTRA 14251A
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21.
Which metal is nonferrous?
A.
B.
C.
D.
22.
What element or base metal is alloyed with copper to produce bronze and is
alloyed with lead to produce soft solders?
A.
B.
C.
D.
23.
K-monel
Inconel
Monel
Duralumin
When applying the spark test to a metal, you notice the spark stream has shafts
and forks only. What does this condition indicate about the metal under test?
A.
B.
C.
D.
26.
The metal has been heat-treated.
The alloying elements have been tempered.
The major alloying element has been tested.
The metal has been covered with a tungsten rolled cover.
What alloy contains 64% to 68% nickel, about 30% copper, and small
percentages of iron, manganese, and cobalt?
A.
B.
C.
D.
25.
Zinc
Nickel
Tin
Aluminum
When used in conjunction with a numbering system that classifies different
aluminum alloys, the letter “T” signifies that what action has occurred?
A.
B.
C.
D.
24.
Cast iron
Carbon steel
Aluminum
Pig iron
It is steel having a high-carbon content.
It is steel having a low-carbon content.
It is a nickel alloy.
It is a molybdenum alloy.
What metal produces a spark stream about 25 inches long with small and
repeating sparklers of small volume that are initially red in color?
A.
B.
C.
D.
Nickel
Stainless steel
Grey cast iron
Monel metal
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27.
Which metal produces the shortest length spark stream?
A.
B.
C.
D.
28.
High-carbon steel
Low-carbon steel
White cast iron
Nickel
On which metal does a chip test produce chips that have smooth surfaces and
sawtooth edges?
A.
B.
C.
D.
Low-carbon steel
Cast steel
Aluminum
Monel
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Trade Terms Introduced in this Chapter
Cleaving
NAVEDTRA 14251A
To split or divide by, or as if by, a cutting blow, esp.
along a natural line of division.
1-30
Additional Resources and References
This chapter is intended to present thorough resources for task training. The following
reference works are suggested for further study. This is optional material for continued
education rather than for task training.
Althouse, Andrew D., Carl H. Turnquist, and William A. Bowditch, Modern Welding,
Goodheart-Wilcox Co. Inc., 1970.
Giachino and Weeks, Welding Skills, American Technical Publishers Inc., 1985.
Fundamentals of Machine Tools, TC 9-524, Department of the Army Training Circular,
Headquarter, Department of the Army, Washington D.C, 1996
Welding Theory and Application, TC 9-237, Department of the Army Training Circular,
Headquarters, Department of the Army, Washington D.C., 1993.
Welding Theory and Application, TM 9-237, Department of the Army Technical Manual,
Headquarters, Department of the Army, Washington D.C., 1976.
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CSFE Nonresident Training Course – User Update
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NAVEDTRA 14251A
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